The current scale-up of Option B+ programs for the prevention of mother-to-child transmission (PMTCT) of HIV promises to escalate achievement of two important goals through initiation of antiretroviral therapy (ART) in all pregnant and breastfeeding women: reduced morbidity and mortality for HIV-infected women and decreased HIV transmission from mother to infant. Crucial to the success of the Option B+ strategy is retention in care throughout the PMTCT cascade: from early diagnosis of HIV infection in pregnant women, their engagement in antenatal care, to ART initiation, follow-up antenatal visits, facility-based delivery by skilled providers, and post- delivery care for both the mother ad infant, including determining final HIV infection status for the infant following cessation of breastfeeding. Option B+ was implemented at 10 health facilities in Swaziland on a pilot basis as part of the Situkulwane Lesiphephile-Safe Generations (Safe Generations) study. Preliminary data from this study suggest that at least 50% of the women who initiated PMTCT care under Option B+ at these sites were lost to follow up (LTF). Other studies have also shown high rates of LTF for pregnant women enrolled in ART and PMTCT care, including Option B+. Previous research has shown that substantial proportions of adult HIV patients reported as LTF were either in care at another clinic (i.e., self-transfers) or have died without program awareness of their death. However, little is known regarding outcomes of the women enrolled in Option B+ programs. Thus, we propose to assess the outcomes of women recorded as LTF in Safe Generations study, and their infants, to determine the proportion alive and engaged in care, alive and disengaged from care, and those who have died, as well as infant vital and HIV status. The proposed 2- year study will involve the conduct of telephone and physical tracing of the estimated 500-600 women LTF using contact information provided by patients at initiation of HIV care to assess patient vital status and retention in ART care, reasons for loss from care, along with their infant's vital and HIV status, if latter is available. Information collected from these interviews will be integrated with Safe Generations study data to provide updated patient outcomes and patient reasons for LTF and disengagement. This updated study data will be analyzed to describe levels of engagement at key points throughout the care cascade, identify determinants for LTF and disengagement, and understand common self-identified reasons for disengagement from care throughout the PMTCT cascade. Study findings will provide crucial new evidence to guide interventions to improve Option B+ performance and, consequently, reduce HIV-related mortality among women and bring us closer to the goal of elimination of mother-to-child transmission of HIV.